VOL. XLVII.] PHILOSOPHICAL TRANSACTIONS. 287 



of the wires ; but that when he had done this, he found inequalities still re- 

 maining; and therefore justly concluded, that they arose from the difference in 

 the friction of the different parts of the clockwork, occasioned by the differences 

 in the fluidity of the oil, &c. 



From what has been said above, it appears, that the improvement of clocks, 

 by a contrivance to prevent their inequalities arising from the different lengths 

 of the pendulum, in different seasons of the year, by the effects of heat and cold, 

 was first thought of, and executed, by Mr. George Graham ; and that the ap- 

 plication of wires or bars of two metals, which have different degrees of expan- 

 sion or contraction, to prevent the same inequalities, was also first thought of by 

 Mr. Graham, and first executed by Mr. John Harrison, without the least know- 

 ledge of what Mr. Graham had done before him. 



LXXXIX. On the Cause of Thunder. By Mr. Henry Eeles, dated Lismore, 



Ireland, June 18, IJb'i. p. 524. 



Mr. Eeles's opinion on the cause of thunder is, that it is by electrical explo- 

 sions among the clouds, the fire of lightning and electricity being of the same 

 nature, as had been long before proved by the experiments of Mr. Franklin in 

 America. After the explosion, then the echo of it from the other clouds is the 

 cause of the continued or distant rumbling noise. Mr. E. adds, that he intends 

 afterwards to show, that this fire is a most considerable agent in nature. First, 

 that the ascent of vapour and exhalation is principally owing to it, and that our 

 atmosphere, by that means, is kept more homogeneal than is generally supposed, 

 and fitter for respiration, vision, &c. and that clouds of heterogeneous matter are 

 kept suspended at their usual height merely by this fire. Secondly, that this fire 

 is the cause of the reflection, refraction, and inflexion of light. Thirdly, that it 

 is the cause of that secondary attraction and repulsion, which Sir Isaac Newton 

 has taken notice of. Lastly, he will give some hints of the great use of this fire 

 in animal life, and in vegetation. 



XC. On Mons. DavieVs Method of Couching a Cataract. By Thomas Hope, 



M. D. p. 530. 



Dr. H. states that he had heard of a new method of performing the operation 

 for the cure of the cataract, but did not care to say any thing of it, until he had 

 seen it himself, and had inquired into the success of it. M. Daviel, a surgeon 

 of Paris, was the first who, in 1745, began to put it in practice, and had at last 

 brought it to perfection ; of which he gave a memoir to the Academy of Sci- 

 ences, of 115 operations, 100 of which succeeded. Dr. H. saw him perforin it 

 on 2 persons, of which the following is a description. 



After having placed the patient in a right light in a chair, he places himself 



